CMOS and CCD image sensors have found a wide range of applications in both consumer and industrial products. Such applications include stand-alone digital cameras, night time driving displays for automobiles, computer peripherals, integrated cell phone cameras, etc.
Mobile technology has traditionally focused on the use of CMOS image sensors for image capture. Consumer expectations, however, have driven the market to use high-resolution CMOS image sensor arrays thereby giving rise to a number of problems to the image sensor developer. First, size constraints imposed by mobile technologies require a greater number of pixels per unit area of the array. Pixel size must therefore be decreased in comparison to traditional CMOS pixels. Such decreases in pixel size result in a corresponding reduction in the dynamic range and sensitivity of the pixel. Second, image readout time from such high-resolution image sensor arrays increases with the number of pixels employed in the array. To reduce image degradation resulting from this increase in readout time, an electronic global shutter mechanism should be employed. Pixels employing an electronic global shutter, however, require a large number of components resulting in a corresponding reduction of the pixel fill factor. Accordingly, the present inventors have found a need in the industry for an improved pixel architecture that addresses one or more of these shortcomings.
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